Sugars and sugar syrups are used extensively in the food industry to sweeten products such as bakery goods, beverages, canned fruits, vegetables, confectionery products, dairy products, dehydrated foods, meat products, jellies and preserves. The liquid sugars and sugar syrups are particularly desirable where the water content contributes to the desirable properties of the product. Examples of the commonly used liquid sugars include liquid sucrose, liquid brown sugar, invert sugar syrups, molasses, corn syrup and high fructose corn syrup.
Sugar syrups and liquid sugars, when used as sweeteners in food products are often used in combination with a flavoring agent and a coloring agent. Typical flavors may include, for example, artificial fruit flavors, vanilla and cocoa. The fruit flavors used are generally the artificial flavors since the artificial flavors are often less expensive and more stable than the natural flavors. Natural fruit flavors are not used on a large scale due to their high cost of production and the difficulty of processing the fruit. Natural fruit flavors and fruit juices are inherently less stable than most artificial flavors. During storage, natural fruit flavors often result in discoloration and a loss of the characteristic flavor. The unstable nature of conventional fruit extracts and flavors generally requires a large amount of the component to be used, thereby increasing the cost of the final product.
Conventional production of natural fruit flavors and extracts crush the fruit and separate the pulp to recover the juice. The juice may be concentrated or otherwise treated to recover flavor components. This type of process is quite expensive and requires large quantities of fruit to economically produce the fruit flavor.
The known methods of recovering flavor components are not as efficient as in the recovery of flavors from other materials. Some plant materials, including, for example, black pepper and mint, have a high content of aromatic materials which can be easily extracted by the use of organic solvents or by expressing the plant material. Fruit flavors, however, cannot be effectively obtained by expressing the fruit. The flavor components in the expressed liquid are generally of insufficient concentration to be used as a flavor source. In order to obtain a higher flavor intensity, the fruit juice has to be concentrated. This is usually performed by heating to drive off the water. Heating of the fruit juice has the distinct disadvantage of destroying the thermally labile constituents of the flavor components. These thermally labile constituents are usually responsible for the characteristic flavor and aroma of the fruit. Expressing of fruit flavors from the fruit is not effective in recovering fruit flavors since the aromatic flavor components are not very soluble in water. Generally, organic solvents, such as ethyl alcohol, are necessary for effective flavor extraction. The flavors obtained from fruits by conventional methods require storage in frozen or refrigerated containers.
Corn syrup and high fructose corn syrup are the more frequently used sugar syrups due, in part, to the low cost of producing these syrups. In addition, corn syrups are generally shelf stable and some corn syrups are sweeter than sucrose. Corn syrups are also desirable since they tend to impart a desirable texture or body to the food product. For example, corn syrups are suitable for imparting a more acceptable mouth feel in canned fruits and beverages. In ice cream, sherbets and other frozen desserts, corn syrups are used to obtain the desired degree of body and texture. The type of corn syrup and the amount used in these products are determined by the desired qualities of the finished food product. In general, increasing the amount of corn syrup will produce a product of greater chewiness. Corn syrup is typically used in enhancing the chewiness of many types of cookies and other bakery products.
High fructose corn syrup is generally sweeter than standard corn syrup and is therefore used extensively as a sweetener. High fructose corn syrup has basically different properties than standard corn syrup. In high fructose corn syrup, the average molecular weight of the sugar is lower than other corn syrups so that the osmotic pressure will be higher in high fructose corn syrups at the same solids concentration. High fructose corn syrup is often used to promote browning reactions with amino acids and in fermentation processes since nearly 100 percent of the sugars are fermentable.
Corn syrups and corn sugars are produced by chemical or enzymatic hydrolysis of starch. The starch may be derived from any source, although in practice the sugars are almost exclusively produced from milo and corn starches. In recent years the changes in the food industry have resulted in corn syrups which have highly selective properties. There are commercially available syrups which have a variety of carbohydrate compositions with varying degrees of viscosity, sweetness and humectancy.
The hydrolysis of starch for the production of corn syrups is accomplished by three different methods. In manufacturing terminology, the terms "conversion" or "starch conversion" are used to denote these three processes. The selection of the type of conversion method is dependent upon the type of corn syrup that is to be produced. The degree of conversion is usually measured in terms of dextrose equivalent. This term is defined as the percentage of reducing sugars in a corn syrup calculated as dextrose on a dry weight basis.
The three processes of starch hydrolysis are acid conversion, acid enzyme conversion and enzyme-enzyme or multiple enzyme conversion. In the first of these methods the only starch hydrolyzing agent is an acid. In the remaining two processes the use of two hydrolyzing agents is required and these procedures are therefore termed "dual conversion." The purposes of the dual conversion systems are twofold. In the first place, acid conversion produces syrups which have limitations on acceptability when the hydrolysis is carried beyond about 55 DE. Secondly, dual conversion methods make it possible to produce syrups having widely different chemical and physical properties.
Processes of drying fruit or treating fruit to extend its shelf life generally involve immersing the fruit pieces in an infusion solution prior to the drying step. The preparation of infused fruit products has conventionally been carried out by adding fresh fruit to a tank containing a warm concentrated sugar solution or sugar syrup. The sugar solution has a greater amount of dissolved solids compared to that present in the fruit. As a result, osmotic exchange takes place, resulting in the infusion of sugar solids into the cellular portions of the fruit. During osmosis, the sugar diffuses inwardly into the fruit while water contained within the fruit diffuses outwardly through the cell walls of the fruit.
One example of an infusion solution for treating fruits is described in U.S. Pat. No. 4,551,348. The disclosed infusion solution is made up of an aqueous solution of an edible acid and sugar. The solution includes at least 35 percent to 100 percent fructose. The fruit pieces are immersed in the solution for a sufficient period of time to infuse the fruit. The solution is disclosed as being concentrated and mixed with the infused fruit during packaging of the fruit product.
Another method of infusing fruits is disclosed in U.S. Pat. No. 4,350,711. A commercially available corn syrup is used as the infusion solution. The fruit is mixed with the syrup and infused for a sufficient period of time. The fruit is then removed and the syrup is drained. Fruit toppings are reported to be prepared by mixing the infused fruit with a portion of the remaining syrup, along with other additives such as a starch, to produce a fruit topping or fruit sauce.
The methods for infusing fruits and producing dried fruits generally have the disadvantage of using substantial amounts of sulfiting agents to inhibit the non-enzymatic and enzymatic browning of the fruit. Increased public awareness and opposition to the sue of sulfiting agents in fruit and vegetable processing have made these processes less desirable. Sulfiting agents have, however, proven effective in inhibiting oxidative deterioration of the dried fruit by scavaging oxygen. The sulfiting agents have also been effective in inhibiting the growth of microorganisms. As a result, the use of sulfiting agents has continued in spite of the disadvantages of using sulfites.
Various techniques have been tried over the years to preserve dried fruits without having to use sulfiting agents. In U.S. Pat. No. 3,754,938 there is disclosed a technique for preserving apple slices using a solution consisting of ascorbic acid, calcium chloride and sodium bicarbonate. The sodium bicarbonate is added to maintain a pH of 7 to 9 during the treatment period. When this treating solution is used it is disclosed that a sulfiting treatment does not have to be used.
Another method is disclosed in U.S. Pat. No. 3,894,157 where the color of freeze dried carrots is stabilized by a treatment with an antioxidant such as ascorbic acid or erythorbic acid. An aqueous solution containing at least one of these acids is sprayed onto the vegetable. When ascorbic acid is used, the concentration of the acid is about 1 to 3 percent of the solution. The treated vegetable is then freeze dried.
The present invention is directed to a method of producing a natural fruit extract which may be used as a sweetener solution containing the natural fruit flavors and fruit sugars. The method involves the infusion of a fresh fruit with a solution containing a sugar and an edible acid. During the infusion of the fruit, the sugar in the solution replaces the monosaccharide content of the fruit. After the infusion process, the infusion solution contains a portion of the flavors, pectins and sugars from the fruit. The infusion solution is suitable as a sweetener for other processes and the infused fruit may be dried for packaging and later consumption.